Optical readers, such as bar code readers, are now quite common. Typically, a bar code comprises a series of encoded symbols, and each symbol consists of a series of light and dark regions, typically in the form of rectangles. The widths of the dark regions, the bars, and/or the widths of the light spaces between the bars indicate the encoded information. A bar code reader illuminates the code and senses light reflected from the code to detect the widths and spacings of the code symbols and derive the encoded data.
Bar code reading type data input systems improve the efficiency and accuracy of data input for a wide variety of applications. The ease of data input in such systems facilitates more frequent and detailed data input, for example to provide efficient inventories, tracking of work in progress, etc. To achieve these advantages, however, users or employees must be willing to consistently use the bar code readers. Many applications require the operator to carry the bar code reader about as the operator moves from place to place and to operate the reader manually to scan codes appearing on different objects. The readers therefore must be easy and convenient to operate and carry.
Many applications additionally require use of the bar code reader with other data input means, for example by incorporation of all the elements into a single integrated data input terminal. Such integrated systems typically include a keyboard, for input of alphanumeric data which may or may not be related to bar code data, a central data processor unit having associated RAM and ROM, and a display. Integrated terminals of this type have been proposed which are small enough to be handheld (see e.g. U.S. Pat. Nos. 4,916,441 and 5,144,120). Such units incorporating so many different elements, however, tend to be larger than many dedicated bar code readers and cumbersome to operate as bar code readers, particularly for extended periods. Also, the prior art integrated devices often require the operator to hold the device in one hand and operate the keyboard with the other. Such operation requires use of both hands and does not allow the user to perform other manual tasks at the same time. These problems, together with problems related to securing and carrying the integrated terminals when not in use, tend to discourage employees from using the data input system, thereby defeating the purpose of the system and particularly the advantages otherwise associated with bar code data entry. Similar problems exist in other types of portable computer or data devices.
From the above discussion of the state of the art, it becomes clear that a need still exists to produce portable computer or terminal systems, particularly ones incorporating an optical reader unit, which are particularly convenient to carry and operate.